When Other Therapies Fail, Deep Brain Stimulation Could Help

Imagine being able to throw the right switch and end severe tremors, excruciating pain, or even deep depression. If it sounds utopian, it's not. That's the promise of a revolutionary surgical procedure called deep brain stimulation, or DBS. Informally, it's sometimes called a "brain pacemaker," and it's been used at Froedtert & The Medical College of Wisconsin since 2005.

Just as a cardiac pacemaker makes the heart work more efficiently by analyzing the heart's rhythms and, if necessary, correcting any abnormalities in its electrical system, a DBS neurostimulator can deliver electrical stimulation to targeted areas in the brain to better control pain, movement, or mental state.

"We're mainly using it right now for treating Parkinson's disease, essential tremor and dystonia (abnormal muscle contractions that may cause involuntary twisting or jerking movements)," says Brian Harris Kopell, MD, a functional neurosurgeon and an Assistant Professor of Neurosurgery at the Medical College. "It's also being investigated for intractable pain as well as some psychiatric disorders such as depression and obsessive-compulsive disorder. We're setting up a limited study here for seizure disorders."

Dr. Kopell and Bradley C. Hiner, MD, an Assistant Professor of Neurology at the Medical College, are co-directors of the Restorative Neurosciences Program at Froedtert & The Medical College. The program offers patients a multidisciplinary approach to treating their conditions when medication and other therapies fail to resolve them - either they've reached the limits of their therapy or they have complications from their medications or other problems, Dr. Kopell says.

Targeting Trouble-Making Neurons
The aim of the DBS surgery - performed while the patient is awake but sedated - is to seek out the neurons that are the source of the Parkinson's tremors, unbearable pain, or other disorder, then stimulating the neurons to perform more normally.

The process begins with a magnetic resonance imaging (MRI) scan to identify and locate the target within the brain where electrical nerve signals generate the symptoms the patient is experiencing, with the patient providing feedback. "Whether it's Parkinson's, essential or familial tremors, dystonia, or Tourette syndrome, the common denominator is to locate the network in the brain where the problem is originating," Dr. Kopell says.

The surgeon - assisted by functional MRI imaging - guides the "lead," a thin tube containing a microelectrode, through a small opening in the skull and implants the tip in the brain. Along the way, the surgeon listens for distinct sounds - the "language of the brain," one surgeon calls it; to the patient, it might sound like static. "Every area of the brain has a distinct electrical signature," is how Dr. Kopell describes it. To help ensure the problem area is isolated, the surgical team talks to the patient as he or she is brought into or out of consciousness throughout the procedure.

Then an insulated wire called an extension is passed under the skin of the head, neck, and shoulder, connecting the lead to a neurostimulator, the third element used in the procedure. The stopwatch-sized neurostimulator (the "battery pack") is usually implanted under the skin near the collarbone. In some cases it may be implanted lower in the chest or under the skin over the abdomen, according to the National Institute of Neurological Disorders and Stroke.

Once the system is in place, electrical impulses are sent from the neurostimulator up along the extension wire and the lead and into the brain. These impulses interfere with and block the electrical signals that cause symptoms.

Although DBS - unlike conventional brain surgery - does not damage healthy brain tissue by destroying nerve cells, it is not without risk, however small the odds. Any brain surgery carries a risk of cerebral hemorrhage - bleeding on the brain, impairment of some functions, stroke, infection, or failure of the implant.

But for some patients who have tried medication, counseling, and myriad other therapies over the years without long-term success, DBS is often worth a try for their debilitating and devastating disorders. "I've seen benefits from DBS in every appropriately chosen patient," says Dr. Kopell.

It's estimated that 30,000-plus patients have undergone the procedure with some success - and for some, almost complete recovery. For example, a patient from northern Wisconsin who underwent DBS recently at the Restorative Neurosciences Program had suffered from Parkinson's disease for 13 years, with his symptoms of uncontrolled shaking growing progressively worse. He could no longer work or participate in his passions of hunting and fishing. His medications became less and less effective, and caused gastric side effects.

In 2005, he decided to try DBS. During the surgery, when the stimulator was activated, his limbs stopped shaking. It was such a dramatic change, at first he thought he was paralyzed. He did not require rehabilitation afterward, although many patients do. In fact, once his stimulator settings were refined over the next two weeks, he eventually needed no medication at all. In many cases, Dr. Kopell says, patients will continue taking some medication, although the dosage and frequency is often substantially reduced.

History and Outlook
The DBS technology was first used in the early 1970s, Dr. Kopell says, but it didn't receive Food and Drug Administration approval for clinical use until the early 1990s. Scientists still do not agree on the precise reason that the procedure works, just that it does work in many cases where other therapies have failed.

Drs. Kopell and Hiner are enthusiastic about the future of DBS - and believe a growing number of conditions might be successfully treated with the surgery. In the future, DBS conceivably could be used to treat tinnitus, autism, drug addictions, and possibly eating disorders. Dr. Hiner has said: "If we can locate the cause of a problem in the brain, there is no reason we can't modulate the activity with this therapy." He believes that within a few years, advances in imaging technology could enable surgeons to perform the DBS procedure without the patient's being awake.

DBS is not a cure, but for carefully selected patients, it can provide an enormous improvement in quality of life - offering partial or complete relief for five to 10 years or even longer, perhaps indefinitely. "It's a wonderful feeling to see the change in patients once their symptoms are relieved," Dr. Kopell says.

Barbara Abel
HealthLink Contributing Writer

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.